Micrometer lapping guide



Nov. 25, 1947, E. D. WILCOX ET AL 2,431,598

MICROMETER LAPPING GUIDE Filed Feb. 20, 1946 @waoiiw Patented Nov. 194.7

MICROMETER LAPPING GUIDE Earl D. Wilcox, Marlboro, and Robert E. Hunt, Northboro, Mass Application February 20, 1946, Serial No. 648,867

1 Claim.

This invention relates to lapping micrometers and more particularly to aguide for the lapping tool.

The primary object of the invention is to in sure the correct apping ofthe anvil and the spindle of a micrometer and accurately dispose thefaces of the anvil and spindle perpendicular to the longitudinal axis ofthe spindle.

Through use the adjacent ends of a micrometer anvil and its cooperatingspindle become worn and it is not infrequent that these adjacentsurfaces get out of line so that they do not lie perpendicular to theaxis of the spindle. When so worn the micrometer loses its accuracy, andfails as a precision tool with the result that it must be subjected to alapping process to bring the faces of the anvil and the spindle back toparallelism and perpendicular to the axis of the spindle.

Another objept of the present invention is to enable the ordinarymechanic skilled in the use of micrometers to lap the adjacent surfacesof the anvil and the spindle, and to bring them back to parallelism andaccurately perpendicular to the axis of the spindle.

The above and other objects may be attained by employing this inventionwhich embodies among its features a sleeve adapted to encircle thespindle of a micrometer, the ends of the sleeve being perpendicular tothe axis of the spindle of the micrometer and means to fix the guide tothe spindle so that a lapping tool may be introduced between the end ofthe guide and the anvil of the micrometer and operated in a planeperpendicular to the axis of the spindle so as to insure accuracy of theanvil.

Other features include having established the perpendicular relationshipof the face of the anvil with the axis of the spindle, reversing thelapping tool, removing the sleeve and proceeding to lap the end of thespindle using the finished face of the anvil as the guide for thelapping tool.

In the drawings:

Figure 1 is a side view of a micrometer showing this improved lappingtool in place on the spindle thereof, the parts of the tool being shownin section to more clearly illustrate the details of construction,

Figure 2 is a perspective view of the lapping tool employed inconjunction with my sleeve and tool guide,

Figure 3 is a perspective view of a modified form of a lapping toolemployed when the span of the micrometer demands a lapping tool ofgreater thickness,

Figure 4 is an enlarged transverse sectional view taken substantiallyalong the line 4-4 of Figure 1, and

Figure 5 is a fragmentary perspective view through the sleeve.

Referring to the drawings in detail a micrometer designated generallyIll comprises a substantially C-shaped frame II carrying at one end ananvil I2 and its opposite end a socket I3 in which the micrometerspindle I4 is mounted. As in conventional micrometers the spindle I 4aligns axially with the anvil I2 and is advanced or retracted withrelation to the anvil through the medium of the thimble I5. Theequipment so far discussed is of conventional form as will be readilyrecognized.

In order to lap the ends of the anvil l2 and the spindle I4 of themicrometer I employ a lapping tool designated generally I6 whichcomprises a disk shaped body I! carrying an axial boss I8 of somewhatlesser diameter than the body I! and formed on the end of the boss I8 isthe lapping surface I9 which is adapted to engage the surface to belapped. It will be understood that the lapping face I9 and the oppositeface of the disk I! lie in spaced parallel planes.

In order to guide the lapping tool l6 and hold the face I9 in properlapping engagement with the end of the anvil I2 I employ a sleeve 20having a bore 2I of somewhat greater diameter than the diameter of thespindle I4. Formed at opposite ends of the sleeve 20 are upset portions22 which extend into the bore to provide guide faces 24 and 25 which lieperpendicular to one another, to form and effect a V-block whichpartially embraces the spindle I4 when the device is in use. Extendingradially through the sleeve 20 diametrically opposite the apex of the Vformed by the faces 24 and 25 is a set screw 26 having a knurled head 2!by means of which the screw may be turned so that its inner end effectsclamping engagement on the spindle I4. Opposite end faces 28 of thesleeve 20 are machined or ground toperfect parallelism, and to lieperpendicular to the axis of the sleeve, and hence the axis of thespindle I4 as established by the surfaces 24 and 25.

When micrometers of greater size are to be lapped I employ instead ofdisk I! a cylindrical body 29 carrying at one end a boss 30 having alapping face 3| which lies parallel to the opposite end of the body 29.

In use the sleeve 20 is mounted on the spindle 24 as illustrated inFigure 1 after which the lapping tool 16 is placed in the position shownin Figure 1 with the back wall of the 'disk resting on the end surface28 of the sleeve 20 and the lapping surface IS in contact with the anvill2. Upon operating the lapping tool I6 in the ordinary manner the faceof the anvil l2 facing the end of the spindle 14 will be brought into aplane lying perpendicular to the axis of the spindle. Having thusestablished and trued the face of the anvil [2, the sleeve 20 is removedfrom the spindle M by loosening the set screw 26 and extracting thespindle from the sleeve after which the lapping tool I6 is reversed soas to rest against the trued surface of the anvil I 2 with the lappingface I9 contacting the end of the spindle I4. position the lapping ofthe spindle may proceed and its absolute parallelism with the adjacentface of the anvil l2 will be assured. In as much as the face of theanvil l2 has already been established as perpendicular to the axis ofthe spindle it is obvious that when the two faces are parallel thespindle face must also be perpendiculartoi its axis;

While in the foregoing there has been shown and described the preferredembodiment of this invention it is to be understood that minor changesinthe details of construction, combina- In this tion and arrangement ofparts may be resorted to without departing from the spirit and scope ofthe invention as claimed.

We claim:

A micrometer lap guide comprising a sleeve adapted to encircle thespindle of a micrometer, said sleeve having a bore of greater diameterthan the diameter of the spindle which it encircles, bearings atopposite ends of the sleeve for enga ing the micrometer spindle, a clampscrew entering the sleeve for cooperation with the bearings to hold thesleeve on the spindle and at least one end surface of the sleeve lyingin a plane perpendicular to the axis of the spindle and the sleeve.

EARL D. WILCOX. ROBERT E. HUNT.

REFERENCES CITED The following references are of record in the fileof'this patent:

Machinery, June 1924, page 802, published by The Industrial Press, 148Lafayette St, New York 13, N. Y. (Copy in Scientific Library.)

